From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58535) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YB4AY-0000Fi-35 for qemu-devel@nongnu.org; Tue, 13 Jan 2015 11:18:14 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YB4AT-0001Xm-2m for qemu-devel@nongnu.org; Tue, 13 Jan 2015 11:18:14 -0500 Date: Tue, 13 Jan 2015 18:17:56 +0200 From: "Michael S. Tsirkin" Message-ID: <20150113161756.GA19566@redhat.com> References: <1419363216-26601-1-git-send-email-mdroth@linux.vnet.ibm.com> <20150112132406.22996.59621@loki> <20150113101219.GB7152@redhat.com> <20150113153442.22996.7921@loki> <20150113155446.GA19259@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150113155446.GA19259@redhat.com> Subject: Re: [Qemu-devel] [PATCH 0/1] pci: allow 0 address for PCI IO/MEM regions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Roth Cc: peter.maydell@linaro.org, aik@ozlabs.ru, qemu-devel@nongnu.org, agraf@suse.de, qemu-ppc@nongnu.org, pbonzini@redhat.com, hw.claudio@gmail.com, david@gibson.dropbear.id.au On Tue, Jan 13, 2015 at 05:54:46PM +0200, Michael S. Tsirkin wrote: > I think we already do this for PC: > commit 83d08f2673504a299194dcac1657a13754b5932a > Author: Michael S. Tsirkin > Date: Tue Oct 29 13:57:34 2013 +0100 > > pc: map PCI address space as catchall region for not mapped addresses > > but we need to find and fix all other targets. BTW this is very easy to test. Add an unused device (like ivshmem) enable BAR, and set it to 0. System should survive, as opposed to hanging. But the big question is whether this is the right thing to do for each platform. For PIIX whatever is not system memory, is PCI. But other boxes might have a different view of the matter. -- MST